<TITLE>WorldWideWeb Address Formats</TITLE>
<NEXTID 20>
<H1>W3 Naming Schemes</H1>(See also: a <A NAME=6 HREF=../DesignIssues/Naming.html>discussion of design issues involved</A> , <A NAME=13 HREF=BNF.html>BNF syntax</A> , <A NAME=19 HREF=../TheProject.html>W3
background</A>)<P>
The format of a hypertext name consists of the name of the naming
sub-scheme to be used, then a name in a format particular to that
subscheme, then an optional anchor identifier within the document.
For example, the format is for all internet-based access methods:<P>
  <A NAME=17>scheme</A> : // host.domain:port / path / path  # anchor<P>
A suffix # anchor id allows one to refer to a particular anchor within
a document.<P>
A suffix ? followed by words separated by + signs  allows one to seach
an index (see <A NAME=15 HREF=Search.html>details</A> ).<P>
References from one document to another with a similar name may be
abbreviated to a <A NAME=8 HREF=Relative.html>relative name</A> . This imposes certain restrictions
on the way that the "path" is represented.<P>
A special format is used to represent a <A NAME=9 HREF=Search.html>search on an index</A> . See also:
the full <A NAME=12 HREF=BNF.html>BNF description</A> , about <A NAME=14 HREF=Escaping.html>escaping illegal characters</A> .
<H2>Examples</H2>
<XMP>
         file://cernvax.cern.ch/usr/lib/WWW/defaut.html#123

</XMP>This is a fully qualified file name, referring to a document in the
file name space of the given internet node, and an imaginary anchor
123 within it.
<XMP>
         #greg

</XMP>This refers to anchor "greg" in the same document as that in which
the name appears.
<H2>Naming sub-schemes</H2>Different schemes usually use different<A NAME=0 HREF=../Protocols/RelevantProtocols.html> protocols</A> on the network.
The format of the address after the scheme name is a function of the
particular scheme. In practice, all internet-based schemes have a
common format for the node name and port.   Schemes currently defined
are as follows, with links to more details.
<DL>
<DT><A NAME=1 HREF=FileAddressing.html>file</A>
<DD> Access is provided to files, using whatever means the browser
and/or gateways have to reach files on obscure machines.
<DT><A NAME=2 HREF=NewsAddressing.html>news</A>
<DD> Access is provided to news articles, and newsgroups, normally
using the NNTP protocol.
<DT><A NAME=3 HREF=HTTPAddressing.html>http</A>
<DD> Access is provided to any other information using the HTTP search
and retrieve <A NAME=16 HREF=../Protocols/HTTP/AsImplemented.html>protocol</A> . The internal addressing of the information
system is mapped onto a W3 path.
<DT><A NAME=10 HREF=TelnetAddressing.html>telnet</A>
<DD> Access is provided by an interactive telnet session. This is
provided ONLY as an interface to other existing online systems which
cannot or have not been mapped onto the W3 space. 
<DT><A NAME=11 HREF=GopherAddressing.html>gopher</A>
<DD> Access is provided using the "gopher" protocol. The gopher
protocol is similar to HTTP but uses separate concepts of menus and
text files rather than hypertext.
<DT><A NAME=18 HREF=WAISAddressing.html>wais</A>
<DD> Access is provided using the WAIS adaptaion of the Z39.50 protocol.
<DT>x500
<DD> Format to be defined.
</DL>
Systems (such as WAIS) which are not currently accessed directly be
W3 servers may be accessed though gateways, in which case the document
address is encoded within the http address of the document in the
gateway.  Browsers which do not have the ability to use certain protocols
may (in principle) be configured to automaticaly use certain gateways
for certain addressing schemes.<P>
This will allow, for example, simple PC-based clients to follow links
through X500 name servers.</A>